Officers were called to Orbital Retail Centre, in Cannock, before 4pm on Monday, September 14, to reports of a 47-year-old man being stabbed following an altercation.
He was taken to hospital with serious injuries to his hand.
A 46-year-old man, from Birmingham, was arrested on suspicion of assault occasioning actual bodily harm. He has since been granted conditional police bail.
Detective Constable Toni Sunderland, from Staffordshire Police's CID South, said: “Our investigation is still in its early stages and we are still eager to speak to anyone who may have witnessed what happened on Monday afternoon.
“We are in the process of carrying our local enquiries but if anyone has any CCTV or dash-cam footage of the incident then we would invite them to get in touch.”
Anyone with information is urged to call Staffordshire Police on 101, quoting incident number 496 of September 14.
Alternatively, contact Crimestoppers anonymously on 0800 555111 or at crimestoppers-uk.org